[sdiy] Using Cortex Mx Arms in Synth DIY

[James Patchell]

     The recent thread aabout the NXP Arm Cortex M0 in a dip package has 
got me thinking about using Arms again instead of an 8 bit micro like 
the AVR.

     The AVR is my primary processor at the moment because it is:
         1. Inexpensive
         2. Fast
         3. Has Excellent development support for Free. (GNU GCC)
         4. Relatively easy to use.  In fact, very easy to use.

     The Cortex Mx processors are:
     1. Very Inexpensive
     2. Very6 FAST!
     3. Free Developement  Tools?
     4. Easy to use?

     The main problem is the development tools.

      NXP has LPCexpresso which has a code size limited compiler (64IK) 
that is basically free.  This software is produced by Code Red.  For 
most SDIY projects, I bet this would work just fine.

     Yagarto is completely free.  It is a community supported gcc for 
the arm and right now I believe it works under Windows, Linux and 
MacOS.  It can be connected up to Eclipse and provides debugging.  Don't 
really know if I would call this easy to use.

     Rowley CrossWorks is almost free ($150 for a personal license).  
Again, this is gcc, but comes with a set of much improved libraries and 
it does have a nice user interface (IDE).  I have used Rowley to work 
with Arms in the past, however, I don't know if I would call it easy to use.

     For debugging and programming, JTAG interfaces can range from 
basically free to quite expensive.  I have a J-Link that came with an 
Arm dev kit.  I*f you buy the JLink by itself, it can be quite pricey.  
There is an open source JTAG interface that uses an FTDI chip.  These 
are fairly reasonable, but I don't know how difficult it is to get one 
to work.

     And as far as the processors go, well, of course there are the DIP 
processors from NXP.  Any of these is a good choice probably for a MIDI 
interface.  Several comanies offer "Stamp" boards with a cortex M3 on 
it.  Some of them are kind of klugy, some look pretty nice.  All of the 
make it easy to interface to the hardware with something that resembles 
at least a DIP form factor.  Most of them, however, seem to use only an 
RS232 boot loader for programming, and don't seem to have a JTAG port 
which is needed for debugging.  Some of them seem to combine the two and 
have a USB port to program and debug with.

Anybody Elese have any thoughts?

-Jim